The Alkylureas are relatively effective inhibitors of the gelation of sickle hemoglobin, and as such represent a group of potentially significant anti-sickling reagents. Twenty new compounds of this family were synthesized wth varying alkyl chain lengths of 2 to 8 carbons and substituent -OH groups, or a second urea group located at the end of the alkyl chain. The hydroxyureas synthesized have -OH groups at the hydrocarbon end or at the polar end of the molecule, located next to the urea group. The latter compounds also include three cyclic hydroxyureas. Two of the diureas prepared so far have solubilizing nitrogen or sulfur atoms introduced in the hydrocarbon chains connecting the two urea groups at the end of the molecules. The effects of representative members of these compounds on the conformation of horse hemoglobin and myglobin were examined using optical rotatory dispersion measurements. The results obtained so far suggest that at the low concentrations usually employed in hemoglobin S gelation experiments few if any of the new inhibitors should produce complications due to denaturation or other conformational alterations of the hemoglobin molecule. Related studies are in progress regarding the relative effectiveness of these compounds as denaturants and dissociating or depolymerizing reagents of protein aggregates, such as deoxyhemoglobin S.